The present invention relates to trigger switch mechanisms of pneumatic nail guns, and more particularly to a switch mechanism pivotally attached in a trigger of a nail gun, for switching the nail gun to operate in one of a sequential actuation mode and a contact actuation mode.
Pneumatic nail gun generally utilizes a compressed high pressure air in an air chamber thereof to drive a hitting rod to hit a nail, for join two objects by activating a nail through both objects, which are widely used in woodworking. The operation of the hitting rod is jointly controlled by a trigger and a safety slide rod of the nail gun.
Actuating nails of a nail gun generally can be divided into two types: sequential actuation mode and contact actuation mode.
For sequential actuation mode, before driving the nails, the operator should press a safety slide rod or a hitting base on the safety slide rod contacting on a surface of a workpiece to push a blocking piece in a trigger upwardly move, and then press the trigger to induce the blocking piece to move with the trigger, for actuating a trigger valve to set the nail gun in the status of hitting nails. If the operator wants to drive the nails again, he or she has to release the trigger firstly, and then repeat the process of pressing the trigger. If the operator disobeys the operating sequence, i.e. pressing the trigger firstly, and then pressing the safety slide rod or the hitting base, the blocking piece in the trigger cannot be induced to move with and the trigger valve cannot be actuated. That is, the nails are restrained. In other words, even if the operator wrongly touched the safety slide rod or the hitting base after the trigger is pressed, the dangerous of unexpectedly hitting the nails are avoided.
The contact actuation mode behave in another manner, before driving the nails, the operator should continuously press the trigger, and then let the safety slide rod or the hitting base to contact hit the surface of the workpiece, which induce the blocking piece to upwardly move for actuating the trigger valve in each hitting process. In addition, the contact actuation mode also allows that the operator sets the safety slide rod or the hitting base on the surface of the workpiece in advance, to induce the blocking piece to upwardly move, and then individually or continuously presses the trigger to respectively drive single or multiple nails for nailing the workpiece.
These two actuation modes have been employed in a conventional nail gun via utilizing a switch mechanism disposed in the trigger to realize switching the operation modes of one of the sequential actuation mode and the contact actuation mode. For example, U.S. Pat. No. 6,588,642 disclosed a biased adjusting rod pivotally attached in a trigger, which includes a pressing spring, a pressing plate, and a rotatable button. The biased adjusting rod can induce a top blocking piece to upwardly or downwardly move in the trigger so as to control the against portion of the top blocking piece relative to a safety plate. Then the stapler can be switched between the operation modes of the sequential actuation mode and the contact actuation mode.
When switches the operation modes, it needs the operator to press the pressing plate and the rotatable button at the same time. However, during the process of operating the nail gun, the operator has to grasp the workpiece or tools by another hand. In other words, in most working environments, such as nailing the workpiece in a high place, the operator cannot conveniently switch the switch mechanism in the trigger by both two hands. Furthermore, the biased adjusting rod is pivotally attached to a pivot plate in the trigger, which makes the structure of the trigger unduly complicated, and increases the manufacturing cost of the trigger.
Accordingly, what is needed is a trigger switch mechanism of a nail gun that can overcome the above-described deficiencies.